A number of processes for the preparation of hyodeoxycholic and chenodeoxycholic acids starting from swine bile are known, for example those disclosed in U.S. Pat. No. 2,758,120, U.S. Pat. No. 3,006,927 and U.S. Pat. No. 5,349,074. The method's known to date are however complex, hence poorly suited to an industrial scale, nor they afford the desired products in sufficient purity for the direct use in therapy or as intermediates in the preparation of other active pharmaceuticals such as ursodeoxycholic acid.